Aadi Krithigai, or Karthigai, is a festival celebrated by Lord Muruga devotees, especially by Tamilians. It is celebrated on the Karthigai star in the Tamil Month Aadi. The festival is also referred as Aadi Krittika and Krithika. In 2014, date of Aadi Karthigai is July 21.

Another popular day associated with Karthigai is the Karthigai Deepam, which falls in the Karthigai month.

Legend has it that Lord Muruga or Skanda was born as six different babies and it was Goddess Parvati who joined the Six to create the powerful Muruga or Kartik, who is the commander of the army of the Devas.

But before conjoining the six different babies were looked after six mothers – the six Karthigai stars.

Karthigai Nakshathram day is considered highly auspicious to worship Muruga and especially when the Krithigai star day in the month Aadi. Lord Muruga Temples in Tamil Nadu, Kerala, Sri Lanka, Malaysia, South Africa and Singapore have special rituals and poojas on the day.